Algal bio-adhesive

ABSTRACT

An algal bio-adhesive comprising algae mass, a crosslinking agent and an inorganic filler.

RELATED APPLICATIONS

This application claims the benefit of priority under 35 USC § 120 ofU.S. patent application Ser. No. 15/110,425, filed on Oct. 6, 2016,which is a U.S. national phase application based on PCT/GB2015/050668under 35 USC § 371, filed on Mar. 6, 2015, the contents of which areincorporated herein by reference in their entireties.

DESCRIPTION 1 Field of Invention

This invention concerns novel water-resistant and versatile adhesiveproducts and glue derived from grain-based ethanol production byproductsincluding CDS (condensed distiller's solubles), DDG (Distiller's DriedGrain), DDGS (Distiller's Dried Grains and Solubles) and WDG (WetDistiller's Grain) materials. In this patent, the term Distiller's Grain(DG) is used in general. In particular, the processed DG bio-adhesivesaccording to this invention have strong dry and wet strength and arethus useful as formaldehyde-free wood adhesive to replace currently usedformaldehyde based wood adhesives. The invention further relates toDG-derived glues and adhesive products containing a cross-linked networkwhich can be further processed into powder form to become adhesive gelor aqueous glue.

Background Art and Related Disclosures

Due to the inherently finite nature of fossil fuel resources, the worldfaces the challenge of finding suitable renewable substitutes that canbegin to replace petrochemicals both as a source of energy and as asource of materials for plastics, rubbers, fertilizers, and finechemicals. More recently, biofuels have been endorsed as a key componentof national and international strategies to reduce greenhouse gas (GHG)emissions and mitigate potential climate change effects.

Two biofuels, ethanol (ethyl alcohol) and biodiesel from fatty acidmethyl esters account for the vast majority of global biofuel productionand use today. These biofuels are made primarily from agriculturalcommodities, such as grain and sugar cane beet molasses, cassava, whey,potato and food or beverage waste for ethanol and vegetable oil forbiodiesel.

In 2010, approximately 87 billion litres (23 billion gallons) of ethanolwere produced, with the United States, Brazil, and the European Unionaccounting for 93% of this output (RFA, 2011a), which leaves largequantities of DG byproducts, mainly used for animal feeds.

Two processes are primarily used to make ethanol from grains: drymilling and wet milling. In the dry milling process, the entire grainkernel typically is ground into flour (or “meal”) and processed withoutseparation of the various nutritional component of the grain. The flouris slurred with water to form a “mash”. Enzymes are added to the mash,which is then processed in a high-temperature cooker, cooled andtransferred to fermenters where yeast is added and the conversion ofsugar to ethanol begins. After fermentation, the resulting ethanolcontaining mixture “beer” is transferred to distillation columns wherethe ethanol is separated from the residual “stillage”. The stillage issent through a centrifuge that separates the solids from the liquids.The liquids, or solubles, are then concentrated to a semi-solid state byevaporation, resulting in condensed distiller's solubles (CDS) or“syrup”. CDS is sometimes sold direct into the animal feed market, butmore often the residual coarse grain solids and the CDS are mixedtogether and dried to produce distiller's dried grain with solubles(DDGS). In the cases where the CDS is not re-added to the residualgrains, the grain solids product is simply called distiller's driedgrain (DDG). If the distiller's grain is being fed to livestock in closeproximity to the ethanol production facility, the drying step can beavoided and the product is called wet distiller's grain (WDG). Becauseof various drying and syrup application practices, there are severalvariants of distiller's grain (one of which is called modified wetdistiller's grain), but most product is marketed as DDGS, DDG or WDG.Some dry-mill ethanol plants in the United States are now removing crudemaize oil from the CDS or stillage at the back end of the process, usinga centrifuge. The maize oil is typically marketed as an individual feedingredient or sold as a feedstock for further processing (e.g. forbiodiesel production). The co-product resulting from this process isknown as “oil extracted” DDGS or “de-oiled” DDGS. These co-productstypically have lower fat content than conventional DDGS, but slightlyhigher concentrations of protein and other nutrients. A very smallnumber of dry-mill plants also have the capacity to fractionate thegrain kernel at the front end of the process, resulting in theproduction of germ, bran, “high-protein DDGS” and other products (RFA,2011b). In some cases, ethanol producers are considering using thecellulosic portions of the maize bran as a feedstock for cellulosicethanol. The majority of grain ethanol produced around the world todaycomes from the dry milling process. In the wet milling process, shelledmaize is cleaned to ensure it is free from dust and foreign matter.Next, the maize is soaked in water, called “steepwater”, for between 20and 30 hours. As the maize swells and softens, the steepwater starts toloosen the gluten bonds with the maize, and begins to release thestarch. The maize goes on to be milled. The steepwater is concentratedin an evaporator to capture nutrients, which are used for animal feedand fermentation. After steeping, the maize is coarsely milled incracking mills to separate the germ from the rest of the components(including starch, fibre and gluten). Now in a form of slurry, the maizeflows to the germ separators to separate out the maize germ. The maizegerm, which contains about 85% of the maize's oil, is removed from theslurry and washed. It is then dried and sold for further processing torecover the oil. The remaining slurry then enters fine grinding. Afterthe fine grinding, which releases the starch and gluten from the fibre,the slurry flows over fixed concave screens which catch the fiber butallow the starch and gluten to pass through. The starch-glutensuspension is sent to the starch separators. The collected fibre isdried for use in animal feed. The starch-gluten suspension then passesthrough a centrifuge where the gluten is spun out. The gluten is driedand used in animal feed. The remaining starch can then be processed inone of three ways: fermented into ethanol, dried for modified maizestarch, or processed into maize syrup. Wet milling procedures for wheatand maize are somewhat different. For wheat, the bran and germ aregenerally removed by dry processing in a flour mill (leaving wheatflour) before steeping in water.

In 2010, an estimated 142.5 million tonnes of grain was used globallyfor ethanol (F. O. Licht, 2011), representing 6.3% of global grain useon a gross basis. Because roughly one-third of the volume of grainprocessed for ethanol actually was used to produce animal feed, it isappropriate to suggest that the equivalent of 95 million tonnes of grainwere used to produce fuel and the remaining equivalent 47.5 milliontonnes entered the feed market as co-products. Thus, ethanol productionrepresented 4.2% percent of total global grain use in 2010/11 on a netbasis. The United States was the global leader in grain ethanolproduction, accounting for 88% of total grain use for ethanol. TheEuropean Union accounted for 6% of grain use for ethanol, followed byChina (3.4%) and Canada (2.3%). The vast majority of grain processed forethanol by the United States was maize, though grain sorghum representeda small share (approximately 2%). Canada's industry primarily used wheatand maize for ethanol, while European producers principally used wheat,but also processed some maize and other coarse grains. Maize alsoaccounted for the majority of grain use for ethanol in China.

There is huge existing market of wood glue for wood panel industry.Organic polymers of either natural or synthetic origin are the majorchemical ingredients in all formulations of wood adhesives.Urea-formaldehyde is the most commonly used adhesive, which can releaselow concentrations of formaldehyde from bonded wood products undercertain service conditions. Formaldehyde is a toxic gas that can reactwith proteins of the body to cause irritation and, in some cases,inflammation of membranes of eyes, nose, and throat. It is a suspectedcarcinogen, based on laboratory experiments with rats.

Phenol-formaldehyde adhesives, which are used to manufacture plywood,flakeboard, and fiberglass insulation, also contain formaldehyde.However, formaldehyde is efficiently consumed in the curing reaction,and the highly durable phenol-formaldehyde, resorcinol-formaldehyde, andphenol-resorcinol-formaldehyde polymers do not chemically break down inservice to release toxic gas. However, it uses the petroleum-basedresource and also expensive.

Increasing environmental concerns and strict regulations on emissions oftoxic chemicals have forced the wood composites industry to developenvironmentally friendly alternative adhesives from abundant renewablesubstances such as soybean protein, animal, casein, vegetable, andblood. Also, adhesives from lignin, tannin, and carbohydrates have beenstudied for replacement of synthetic adhesives that are dominatinglyused in the manufacture of wood composite products. These adhesives aregenerally used for non-structural applications, due to their poor waterresistance and low strength properties.

Modifications including further purification to obtain high proteincontents, increases of the specific surface area of the materials,denaturation of the protein by acid, alkaline and surfactants have beenshown to be useful to enhance the wood adhesive strength of soy basedglue, or mixed with other synthetic adhesives such as phenolformaldehyde resin which increase the cost for manufacturing.

It would, therefore, be advantageous to provide renewable bio-adhesiveswhich are able to be used as wood adhesives with comparable strength asthe synthetic wood adhesives such as formaldehyde based glue.

It is, therefore, a primary objective of the present invention toprovide a stable adhesive generally inexpensive and versatile.

It is, therefore, a further object of the present invention to provide astable aqueous adhesive comprising DG-material derived from ethanolproduction, and that are safe, water-resistant for wood application. TheDG materials include DDGS, CDS, DDG and WDG from byproducts of ethanolproduction plant.

It is a further object of the present invention to prepare DG basedadhesive products that are produced by mixing dry DG materials withadditives and further milled into fine powder for greater adhesivestrength properties to broaden their suitability for adhesiveapplications, easy in storage for longer shelf-life and transportation.

It is yet a further objective of the invention to prepare DG basedadhesive products that are produced by mixing dewatered DG materials,e.g. WDG and CDS (water content less than 70%) with additives andhomogenised into aqueous bio-adhesives.

It is yet a further object of the invention to prepare an adhesive thatconsists essentially of byproducts of after ethanol distillation duringethanol biofuel process.

It is yet another object of the invention to prepare adhesive productsthat comprise naturally DG materials in dry form (e.g. DDGS and DDG)that are blended with a crosslinking agent to form a crosslinked networkto enhance the water resistance of the adhesives.

It is further another object of the invention to mill the above mixtureto greater than 80 meshes for formulation into aqueous adhesives.

It is yet another objective of the invention to prepare adhesiveproducts that comprise above aqueous adhesives and a crosslinking agentand/or wet-strengthen agent for water-resistant wood industryapplication.

DETAILED DESCRIPTION OF THE INVENTION

The current invention concerns novel bio-adhesives derived from DGmaterials.

According to a first aspect of the invention there is provided DG basedbio-adhesives consisting of DG mass, crosslinking agents and inorganicfillers, optionally other additives for making aqueous DG bio-adhesives.

According to a second aspect of the invention there is provided aprocess for manufacturing such DG based bio-adhesives, the processcomprising the steps of:

-   -   a. Combining DG material obtained directly from ethanol        production plant, such as DDGS, DDG, CDS and WDG with defined        dryness and suitable protein content, a cross-linking agent, and        fillers to form a blend using a mechanical mixer or blender,    -   Whereas in step a: the DG material has the water content less        than 70%; preferably less than 40%; most preferably less than        20%;

the crosslinking agent is selected from a organic polymeric materialwith crosslinkable groups such as poly-isocyanate, epoxy resin, or aninorganic material such as silicates, borates or mixture of polymericcrosslinker and the inorganic substance;

the fillers are calcium materials such as calcium oxide, calciumhydroxide, calcium chloride, calcium carbonate, calcium sulfate,preferably calcium oxide, calcium sulfate which can dewater during theblending process. The DG material in the blend has the content between50-89%, crosslinking agent has 1.0-20%, and fillers are 10-30%.

-   -   b. Milling the blend via a micronisation milling machine or any        other chosen mechanical wet or dry milling machine to produce        fine powdery material with particle size between 80-600 meshes,        preferably, between 100-500 meshes, most preferably 200-300        meshes.    -   c. Mixing the powdery material with additional water, optionally        with addition of a defoamer or an anti-foaming agent, a        thickener and optionally with a crosslinking agent or        wet-strength agent, wherein defoamer is selected from food grade        deformer used in milk, protein process industry, such as mineral        oil, vegetable oil or white oil based deforming agent; the        thickener selected are food grade water soluble natural polymer        such as cellulose derivatives e.g. HPMC, CMC, proteins such as        gelatin, alginate, chitosan; and water soluble polymers such as        Polyvinyl alcohol (PVA), sodium polyacrylic acid (PAA) or it's        copolymer. The wet strength agent is        polyamideamine-epichlorohydrin (PAE), the crosslinking agent is        a polymeric isocyanate or polymeric isocyanate with the        isocyanate group blocked to obtain DG aqueous bio-adhesives with        solid content between 20-60%, preferably 20-50%, most preferably        20-40%.

According to the invention there is provided a process for manufacturingDG based bio-adhesives, the process comprising the steps of:

-   -   a. combining DG material, a cross-linking agent and inorganic        fillers to form a blend by mechanical blender;    -   b. Micronising or mechanical milling the blend to obtain powdery        material; and    -   c. Mixing the powdery material with additional water, optionally        with the addition of other additives such as defoaming agent,        thickener, wet strength agent and a crosslinking agent to form        DG based bio-adhesives.

DG biomass contains lipids, proteins, and carbohydrates that mainly isused for animal feed. Compared to soy meal, the protein content isranged from 20-40% depending on the process of the byproduct. Typicallyfor DDGS, the protein content is between 20-30%. Due to the nature ofthe origin, the cost of DG is much lower than that of soy meal. Forexample, the price of DDGS is about ½-⅓ of the price of soy flower.

Surprisingly it was found that DG containing 20-30% protein (dry mass)without further expensive refining to increase the protein content canbe used for the current process to produce bio-adhesives. The DG biomassis the by-products directly from ethanol production plant, which arereadily available as animal feed material, including CGS, DDG, DDGS andWDG. The quantity required for the formulation can be adjusted accordingto the protein content and the solid content of the mass.

The crosslinking agent used in current invention is polymeric isocyanatewhich is used to produce polyurethane. The polyisocyanate functionalgroups used in current invention include PMDI, PHDI, Polyurethanepre-polymer, blocked polyisocyanates such as polyisocyanates withphenol, ε-caprolactam blocked. A blocked polyisocyanate can be definedas an isocyanate reaction product which is stable at room temperaturebut dissociates to regenerate isocyanate functionality under theinfluence of heat around 100-250° C. Blocked polyisocyanates based onaromatic polyisocyanates dissociate at lower temperatures than thosebased on aliphatic ones. The dissociation temperatures of blockedpolyisocyanates based on commercially utilized blocking agents decreasein this order: alcohols>ε-caprolactam>phenols>methyl ethylketoxime>active methylene compounds.

Other crosslinking agent can be used in current invention includeepoxy-resins. Epoxy resins, also known as polyepoxides are a class ofreactive prepolymers and polymers which contain epoxide groups. Epoxyresins are polymeric or semi-polymeric materials and An importantcriterion for epoxy resins is the epoxide content. This is commonlyexpressed as the epoxide number, which is the number of epoxideequivalents in 1 kg of resin (Eq./kg), or as the equivalent weight,which is the weight in grams of resin containing 1 mole equivalent ofepoxide (g/mol). One measure may be simply converted to another:

Equivalent weight(g/mol)=1000/epoxide number(Eq./kg)

The epoxy resin can be used in current invention include Bisphenol Aepoxy resin, Bisphenol F epoxy resin, Aliphatic epoxy resin andGlycidylamine epoxy resin.

The content of the polymeric crosslinking agent mixed with DG materialsis between 1.0-20%.

Other crosslinking agents can be used include inorganic materials suchas silicates and borates which can be used separately or mixed withabove polymeric crosslinking agent.

The total content is in the range of 1.0-20%, preferably in the range of1-10%, most preferably in the range of 5-10%.

The fillers used for current application are calcium based inorganicmaterials. They can be used to adjust the water content of the DGmaterials and the reheological properties of the final bio-adhesives.They can also be useful to help the subsequent dry milling process.

The more calcium materials are incorporated, the more dry blend can beobtained. The typical content of the calcium materials such as singlecalcium oxide, calcium chloride calcium carbonate and calcium sulfate ortheir mixtures is in the range of 10-30%. The optimised composition foreasy to dry mill can be adjusted by changing the ratio of DG mass andthe fillers.

After the blending with an industrial mechanical blender, the mixtureneeds to be stored for overnight (>8 hrs) before milling. The finepowder will give a homogenized mixture in order to swell in water toform bio-adhesives for easy to spray or spread for applications.

The milling process can be performed by readily available micronisationequipments, or mechanical milling machines. The particle size obtainedis controlled at 80-600 meshes, preferably at 100-500 meshes, mostpreferably at 200-300 meshes. When WDG is used, the milling can beachieved by homogenization process, which can directly lead to finalaqueous bio-adhesives.

The DG bio-adhesives can be formulated by adding above milled powderinto premeasured water in a batch vessel with a mixer or pumping into amechanical static mixer with calculated amount of water, or into a batchhomogeniser or online homogeniser for continuous formulation of theaqueous bio-adhesives.

The solid content of the formed bio-adhesives is between 20-50% andpreferably between 20-40%.

Optionally, in the formulation of the aqueous bio-adhesives, someadditives can be added for easy manufacturing, optimized viscosity andenhanced wet strength for applications.

The additives include defoamer or an anti-foaming agent, a thickener andoptionally with a crosslinking agent or wet-strength agent, whereindefoamer is selected from food grade deformer used in milk, proteinprocess industry, such as mineral oil, vegetable oil or white oil baseddeforming agent; the thickener selected are food grade water solublenatural polymer such as cellulose derivatives e.g. HPMC, CMC, proteinssuch as gelatin, alginate, chitosan etc; or water soluble hydrogel suchas PVA, PAA and PAA copolymer, the wet strength agent ispolyamideamine-epichlorohydrin (PAE), the crosslinking agent is apolymeric isocyanate or a polymeric isocyanate with the isocyanate groupblocked. The percentage of the additives considered to be added is inthe range of 0.01-5%, preferably in the range of 0.1-5%, most preferablyin the range of 0.5-5%.

The main application of current invention of DG bio-adhesives is in thefield of production of wood based panels to replace formaldehyde basedwood adhesives. The wood based panels include plywood, fibreboard andparticle board.

The DG bio-adhesives can also be used for making paper-based board suchas paper packaging board, cardboard, carton packaging material forrecyclable food packaging, gift packaging and medical packaging. Otherapplications include adhesives for furniture used in hospital andschool. The bio-adhesives can also be used to make fibreboard based onnon-wood materials such as straw. The straw based fibreboard can be usedas packaging materials for food. The DG bio-adhesives can also be usedin marine board whereas the highly water-resistant wood board isrequired. Although the invention has been described in connection withspecific preferred embodiments, it should be understood that theinvention as claimed should not be unduly limited to such specificembodiments, various applications of the described modes of carrying outthe invention which are obvious to those skilled in the art are intendedto be covered by the present invention.

The invention now will be further exemplified.

Example 1: Preparation of DDGS Based Bio-Adhesive

DDGS, water content 10%, protein content 26%, lipid content 5%, was fromUSA. In a mechanical blender (250 KG volume capacity), 50 kg of theDDGS, 10 kg of calcium oxide powder (200 meshes) and 10 kg of sodiumsilicate was added and mixed for 30 mins and stored for 4 hours. To themixture, 2 kg of PMDI was slowly added during mixing within 20 mins andblended for further 30 mins to obtain a well mixed blend. The blend wassealed and stored overnight for 10 hours, and then transferred to anAir-Jet milling machine to obtain fine powder with particle size around300 meshes. In a 500 L high-shear mixing vessel for producing coatingmaterial, 100 L water was added, and then 50 kg of above milled powderwas added and mixed for 60 mins. 1 Kg PVA powder (1788) was added andmixed for another 60 mins. 100 g of defoaming agent was added to obtainthe DDGS bio-adhesives ready for plywood process. The solid content isabout 33%.

Application of DDGS Bio-Adhesives for Plywood:

5 pieces of poplar veneers were cut into size at 36 cm×36 cm. The abovealgal bio-adhesive was brushed onto one side of the first piece, oneside of the last piece and the two sides of the rest of 3 pieces. Amountof bio-adhesives on each veneer was controlled with a balance. 5 piecesof poplar veneers were cross-staged. Assembled wood specimens werepressed at 3 MPa and 120° C. for 10 min or 150° C. for 5 min with a hotpress. The wood assemblies were conditioned at 23° C. and 50% RH for 48h and then cut into five pieces with overall dimensions of 80×20 mm andglued dimensions of 20×20 mm.

The cut wood specimens were conditioned for 4 additional days at thesame conditions before testing. Shear strength testing was performedusing an Instron (Model 4465; Canton, Mass., USA) at a crosshead speedof 1.6 mm/min according to ASTM Standard Method D906-98(2011). Shearstrength, including dry strength and wet strength, ware performedfollowing ASTM Standard Methods (ASTM D906-98 2011) at maximum load wasrecorded. Values reported are the average of five specimen measurements.

Water resistance test: Specimen was boiled at 100° C. for 2 hours. Thespecimen is removed from water and visually inspected for evidence ofdismemberment.

Comparison of Urea-Formaldehyde (UF) glue and Phenol-Formaldehyde (PF)glue to make plywood: Commercially UF and PF for pressing plywood werecarried out as the method shown in Example 1.

Example 2: Preparation of DDGS Based Bio-Adhesive

DDGS, water content 10%, protein content 26%, lipid content 5%, was fromUSA. In a mechanical blender (250 KG volume capacity), 50 kg of theDDGS, 10 kg of calcium oxide powder (200 meshes) and 10 kg of sodiumsilicate was added and mixed for 30 mins and stored for 4 hours. To themixture, 2 kg of PMDI was slowly added during mixing within 20 mins andblended for further 30 mins to obtain a well mixed blend. The blend wassealed and stored overnight for 10 hours, and then transferred to anAir-Jet milling machine to obtain fine powder with particle size around300 meshes. In a 500 L high-shear mixing vessel for producing coatingmaterial, 150 L water was added, and then 50 kg of above milled powderwas added and mixed for 30 mins. To the mixture, 12.5 kg of PAE and 2.5kg of PMDI was added and mixed for 60 mins. 100 g of defoaming agent wasadded to obtain the algal bio-adhesives ready for plywood process. Thesolid content is about 30%. The plywood using above DDGS bio-adhesivewas produced according to the same method as example 1.

Example 3: Preparation of DDGS Based Bio-Adhesive

DDGS, water content 10%, protein content 26%, lipid content 5%, was fromUSA. In a mechanical blender (250 KG volume capacity), 50 kg of theDDGS, 10 kg of calcium oxide powder (200 meshes) and 10 kg of sodiumsilicate was added and mixed for 30 mins and stored for 4 hours. To themixture, 2 kg of PMDI was slowly added during mixing within 20 mins andblended for further 30 mins to obtain a well mixed blend. The blend wassealed and stored overnight for 10 hours, and then transferred to anAir-Jet milling machine to obtain fine powder with particle size around300 meshes. In a 500 L high-shear mixing vessel for producing coatingmaterial, 100 L water was added, and then 50 kg of above milled powderwas added and mixed for 60 mins. To the mixture, 5.0 kg of PMDI wasadded and mixed for 60 mins. 100 g of defoaming agent was added toobtain the algal bio-adhesives ready for plywood process. The solidcontent is about 35%. The plywood using above DDGS bio-adhesive wasproduced according to the same method as example 1.

Example 4: Preparation of CDS Based Bio-Adhesive

CDS was obtained commercially from ethanol production manufacturer. Thewater content is about 20%, protein content 30%. To a 100 L blender, 10kg of the CDS, 2 kg of calcium oxide powder (200 meshes) and 1 kg ofsodium silicate was added and mixed for 30 mins. To the mixture, 1 kg ofPMDI was slowly added during mixing within 20 mins and blended forfurther 30 mins to obtain a well mixed blend. The blend was sealed andstored overnight for 10 hours, and then transferred to an Air-Jetmilling machine to obtain fine powder with particle size around 300meshes. In a 100 L high-shear mixing vessel for producing coatingmaterial, 40 L water was added, and then 10 kg of above milled powderwas added and mixed for 30 mins. To the mixture, 1.0 kg of PMDI wasadded and mixed for 60 mins. 100 g of defoaming agent was added toobtain the algal bio-adhesives ready for plywood process. The solidcontent is about 20%.

The plywood using above WDG bio-adhesive was produced according to thesame method as example 1.

Example 5: Preparation of WDG Based Bio-Adhesive

WDG was obtained commercially from ethanol production manufacturer. Thewater content is about 70%, protein content 10%. In a 100 L high-shearhomogenizer for producing coating material, 40 L WDG was added, and tothe mixture, 2 Kg sodium silicate, 1 Kg PVA(1788) and 1.0 kg of PMDI wasadded one by one and homogenised for 60 mins. 100 g of defoaming agentwas added to obtain the WDG bio-adhesives ready for plywood process. Thesolid content is about 28%.

The plywood using above WDG bio-adhesive was produced according to thesame method as example 1.

Example 6: Application of DG Bio-Adhesives for Preparation of ParticleBoard

DG bio-adhesive produced in example 2 was used to prepare particleboard. 150 g of DG bio-adhesive was added slowly to 600 g of pine woodparticles having a moisture content of approximately 5% and mixed with amechanical mixer. A 9-inch×9 inch×9 inch wood forming box was centeredon a 12 inch×12 inch×0.1 inch stainless steel plate, which was coveredwith aluminum foil. The wood-adhesive mixture is slowly added into theforming box to achieve a uniform density of particles coated withbio-adhesive. The mixture was compressed by hand with a plywood boardand the wood forming box was carefully removed so that the particleboard matte would not be disturbed. Then, the plywood board was removed,a piece of aluminum foil was placed on the matte, and another stainlesssteel plate was placed on top of the matte. The particle board matte wasthen pressed to a thickness of ¾ inch using the following conditions:120 psi for 10 Ominutes at a press platen temperature of 170° C. Theparticle board was trimmed to 5 inches×5 inches to check the waterresistant property.

Example 7: Application of DG Bio-Adhesives for Preparation of FiberBoard

DG bio-adhesive produced in example 3 was used to prepare fiber board.200 g of DG bio-adhesive was sprayed slowly to 800 g of pine wood fiberhaving a moisture content of approximately 5% while mixing with amechanical mixer. A 9-inch×9 inch×9 inch wood forming box was centeredon a 12 inch×12 inch×0.1 inch stainless steel plate, which was coveredwith aluminum foil. The wood-adhesive mixture is slowly added into theforming box to achieve a uniform density of fibers coated withbio-adhesive. The mixture was compressed by hand with a plywood boardand the wood forming box was carefully removed so that the fiber boardmatte would not be disturbed. Then, the plywood board was removed, apiece of aluminum foil was placed on the matte, and another stainlesssteel plate was placed on top of the matte. The fiber board matte wasthen pressed to a thickness of ¾ inch using the following conditions:120 psi for 10 minutes at a press platen temperature of 170° C. Thefiber board was trimmed to 5 inches×5 inches to check the waterresistant property.

TABLE 1 Test results of plywood produced from algal bio-adhesives inexample 1-7 Water resistance test Dry strength Wet strength (boilingwater for two Plywood (MPa) (MPa) hours) Example 1 1.8 0.8 IntactExample 2 3.0 1.8 Intact Example3 2.5 1.3 Intact Example 4 2.5 1.2Intact Example 5 3.0 1.5 Intact Example 6 / / Intact Example 7 / /Intact Formaldehyde-Urea 2.5 / Dismemberment resin Phenol-Urea resin 3.41.8 intact

DESCRIPTION 2

The present invention is related to a distiller's grain based reinforcedmaterial and its use as a distiller's grain based non-formaldehyde gluefor wood panel applications. Distiller's Grain-based reinforced materialfor wood-based panels and Distiller's Grain-based non-formaldehydeadhesive prepared from Distiller's Grain-based reinforced material.

The invention relates to a distiller's grain-based reinforced materialfor wood-based panels and a distiller's grain-based non-formaldehydeadhesive prepared from the distiller's grain-based reinforced material.The distiller's grain-based reinforced material is a powdery productobtained by stirring, curing and milling the following components byweight percent: 50% to 90% of distiller's grain, 10% to 35% of aninorganic material and 1% to 20% of a high-molecular water-resistantmaterial. The distiller's grain can be one or more of DDGS (DistillersDried Grains with Soluble), DDG (Distillers Dried Grains) and DDS(Distillers Dried Soluble). The distiller's grain-based non-formaldehydeadhesive is prepared by stirring and mixing the following components byweight percent: 20% to 50% of the distiller's grain-based reinforcedmaterial, 0.1% to 5% of additive and water to make up the rest. Thedistiller's grain-based non-formaldehyde adhesive prepared from thedistiller's grain-based reinforced material really realizes the purposeof non-formaldehyde release and can be used for overcoming the defectsof high raw material cost, easy deterioration and poor water resistanceof the existing biological adhesive. The bonding strength and the waterresistance of the distiller's grain-based non-formaldehyde adhesivereach or exceed those of the existing urea-formaldehyde adhesive and theexisting phenol adhesive. Thus, the distiller's grain-based reinforcedmaterial can be used to prepare various types of wood-based panels.

BACKGROUND

The main wood-based panels have four categories including plywood,particle board, block board and fibreboard. Except the manufacturing ofplywood used for the construction mould panels where phenol-formaldehyderesin is used, the mostly wood panels are manufactured usingurea-formaldehyde or melamine modified urea-formaldehyde glue.Therefore, contaminated wood-based panels are mainly due to the releaseof formaldehyde from the adhesives. In order to solve the problem offormaldehyde contamination, new greener formaldehyde-free adhesives withlow-cost and easy adoption by industry has to be researched anddeveloped. In both China and the world, soy based formaldehyde-freebiological glue and starch based glue have been developed. However,there are some disadvantages such as the high prices of raw materials,low bonding strength, poor water resistance and less resistance tomicrobial degradation. Although the performance can be improved throughmodification process of the biological glue, the production cost hasincreased. In addition, the viscosity of soybean biological glue is veryhigh, which leads to the suitability problems in the industrial processof wood based panel. For starch based biological glue, although theprice is lower than soy based biological glue, it has poor waterresistance and does not apply to Class 1, II and III plywood.

DETAILED DESCRIPTION OF THE INVENTION

The first objective of the present invention is to provide a Distiller'sgrain-based reinforced material for wood-based panels, with widelyavailable sources of raw materials, low cost, easy to preserve, andsuitable to make non-formaldehyde glue.

The technical solution to achieve the first objective of the presentinvention is: A distiller's grain based reinforced material used forwood-based panels with characteristics in that it is composed ofdistiller's grain, inorganic material, and polymeric water-resistantmaterial by blending, curing, and milling to obtain a powder. The weightpercentage of each component described above is as follows: 50 to 90%for distiller's grains, 10 to 35% for inorganic material, 1˜20% forwater-resistant polymer material and the sum of the weight percentage ofeach component is 100%; In which, the distiller's grain is one or moreof dried whole stillage of DDGS, distiller's dried crude DDG anddistiller's dried solubles DDS.

The said inorganic material is a calcium compound and/or silicate, inwhich calcium compound and silicate with a weight ratio of 1:0 to 4. Thesaid polymer water resistant material is a polyisocyanate, blockedpolyisocyanates, and one or more epoxy resins.

The preparation method of Distiller's grain-based reinforced materialfor wood-based panels is: According to formulation weight percentage,mix formulated amount of distiller's grains, inorganic material, polymerwater-resistant material to blend for 0.5-1 h, seal the blend to allowto stand overnight for curing, using conventional jet milling equipmentfor milling, collect powdery material sized at the range of 80 to 600mesh to be used as the distiller's grain based reinforced material forwood-based panels applications.

A distiller's grain based reinforced material for wood-based panels withthe characteristics in which the inorganic material of the calciumcompounds can be one or several of the compounds from calcium carbonate,calcium sulfate, calcium chloride, calcium oxide, calcium hydroxide,calcium phosphate, calcium magnesium phosphate. The silicates are sodiumsilicate and/or potassium silicate.

The second objective of the present invention is to provide anenvironmentally friendly, low-cost, good water resistance, high bondingstrength distiller's grain based non-formaldehyde glue.

The technical solution to achieve the second objective is: A distiller'sgrain based non-formaldehyde glue formulated from distiller's grainbased reinforced material for wood-based panels, with thecharacteristics in which it is based on 20-50 wt % of distiller's grainbased reinforced material, 0.1-5 wt % of the additives, the rest weightpercentage amount of water as raw materials. The glue is obtained bystirring and mixing. The additives are one or more of a thickener, adefoaming agent, a wet-strengthen agent and a curing agent.

The non-formaldehyde distiller's grain based adhesive, with thecharacteristics in which the thickener additive is a inorganicthickener, a cellulosic thickener, a natural polymer thickening agent orit's derivative, and a synthetic polymer thickener; The de-foamingadditive is a silicone oil based, a polyether based, a higher alcoholbased, a mineral oil based and a vegetable oil based; The said curingagent additive is one of an organic amine, an organic acid anhydride,and a compound containing imidazole group.

The technical effects of the present invention are: ( ) The technologysolutions to produce Distiller's grain-based reinforced material forwood-based panels are mixing distiller's grain as the main raw materialwith suitable amount of inorganic materials and water-resistant polymermaterials. Distiller's grain is the by-products of the bioethanolproduction using crops such as corn, barley, sorghum, sweet potatoes andso on by fermentation. For example, three tons of corn can produce 1tonne alcohol and 1 tonne distiller's grain. The dried whole stillagecorn DDGS contains 20 to 30% crude protein, 3 to 12% of crude fat andnow is currently limited to be used as a biological protein animal feed.In the present invention, it is unexpected to discover that adistiller's grain based reinforced material for making wood panelscontaining distiller's grains with certain amount of biological protein,fat and cellulose, combining with the suitable amount of inorganicmaterials and water resistant polymer material can be obtained. Thematerial can be used to make non-formaldehyde glue to solve the problemof the release of formaldehyde from wood panels.

The distiller's grain based non-formaldehyde glue derived from theDistiller's grain-based reinforced material with suitable inorganicmaterials and polymer waterproof material can have suitable viscosityand water resistance. With the increased shortage of oil resource,bioethanol derived from corn and wheat, etc by fermentation has becomean important way to solve the energy crisis. Therefore, the productionvolume of the distiller's byproducts will be gradually increased withvery rich sources to meet the needs of industrial production of glue.The distiller's grain based reinforced material can be easy to store andthe Distiller's grain-based formaldehyde-free glue can be formulatedwhen it is needed for wood panel production.

{circle around (2)} Distiller's grain-based non-formaldehyde glue in thepresent invention is easy to prepare. It can be used with the existingprocess for the preparation of various types of wood-based panels togive the bonding strength and water resistance equal or superior toexisting plywood made from phenolic and urea-formaldehyde glue. The woodpanel has no release of formaldehyde from the glue and it is the realgreen products. It also solves the problems of high cost of soybean andblood glue, smells, easy to spoilage and poor water resistance.

SPECIFIC EMBODIMENTS

The following examples of the invention will be further described in theembodiments, but not limited to such specific embodiments.

All the raw materials used in the examples were commercially available,unless it has noted industrial supplies, otherwise it can be purchasedthrough commercial channels.

Example 1B: Preparation of Distiller's Grain-Based Reinforced Materialfor Wood Panels Sample 1˜6

{circle around (1)} Formulation

The weight percentage of the components for present invention to makedistiller's grain-based reinforced material is as follows: 50 to 90%distiller's grain, 10 to 35% inorganic material, water-resistant polymermaterial 1-20%, the total weight percentages of each component is 100%;inorganic material is a calcium compound and/or silicate. The weightratio of calcium compound/silicate compound is 1:0 to 4. The specificformulations are shown in Table 1B.

TABLE 1B 1 2 3 4 5 6 Weight of Weight of Weight of Weight of Weight ofWeight of component component component component component componentComponent (kg) (kg) (kg) (kg) (kg) (kg) Distiller's grain  (62.5%) (62.5%) (64.5%) (64.5%) (66.7%) (66.6%) {circle around (1)}DDG 100 / 50/ / / {circle around (2)}DDS / 100 50 / / / {circle around (3)}DDGS / // 100 100 100 In-organics (31.25%) (31.25%) (25.8%) (32.3%) (23.3%)(16.7%) {circle around (1)}sodium 25 25 25 25 25 / silicate {circlearound (2)}Calcium 10 15 15 / / 25 Carbonate {circle around (3)}Calcium/ 10 / / / / sulfate {circle around (4)}Calcium 15 / / 25 10 / chlorideWater-  (6.25%)  (6.25%)  (9.7%)  (3.2%)   (10%) (16.7%) resistantpolymer {circle around (1)}PHDI / / / 5 / / {circle around (2)}PMDI 10 /15 / 15 25 {circle around (3)}Epoxy resin / 10 / / / / Total 160 160 155155 150 150 Note 1: Data in brackets is the weight percentage for eachcomponent in the distiller's grain based reinforced material. Note 2:dried whole stillage DDGS, dry coarse distiller's grain DDG, distillersdried grains with solubles DDS are prepared by fermentation of cornstarch, by-product of alcohol. Its quality conforms to GB/10647-2008standard; Polyisocyanate PHDI (grades XL600, the Perstorp products,Sweden), polyisocyanates PMDI (grades 44V20, Bayer products); epoxyresin (grade 5881A/B, Zhongshan chemical products); the rest arecommercially available industrial products.

{circle around (2)} Preparation

According to Table 1B, weigh out the formula amount of distiller'sgrain, inorganic materials, polymer waterproof material and transferthem into a 500 L conical mechanical mixing equipment to mix for 0.5 h.After the mixing, the blend is sealed for aging overnight and it ismilled using conventional jet milling equipment to collect 300 meshpowder to obtain distiller's grain-based reinforced material sample 1-6respectively.

Example 2B: Preparation of Formaldehyde-Free Distiller's Grain BasedGlue

The Distiller's grain-based formaldehyde-free glue in present inventionhas the weight percentage of distiller's grain based reinforced materialat 20-50 wt %, the additive at 0.1-5 wt % and the rest being water andit is produced by mixing. The additive is one or several of thickener,de-foaming agent, wet strengthen agent and curing agent.

{circle around (1)} Preparation of Distiller's Grain BasedNon-Formaldehyde Glue Sample 1A˜6A

Weigh 35 kg of sample 1-6 produced according to Example 1B respectively.To each sample, 64.9 kg of water was added and stirred using a highshear mixer used in paint industry at the speed of 300 revolutions/min.After stirring for 1 hour, add 0.1 kg silicone based defoamers (gradesFAG470, Union Carbide Corporation), and mix at 100 rev/min for 1 hour toobtain the Distiller's grain based glue without formaldehyde sample1A˜6A

{circle around (2)} Preparation of Distiller's Grain-BasedFormaldehyde-Free Glue 7A˜8A

Weigh 35 kg of sample 2 and 6 prepared in Example 1B respectively and toeach sample, 59.9 kg of water was added and stirred using a highshearing machine used the paint industry at 300 rpm/stirred for 1 hour.Then 4.9 kg of wet strengthen agent polyamide epichlorohydrin resin(grades MS, Zibo Chemical Co., St. Enoch product) and 0.1 kg siliconebased defoamers (grades FAG470, Union Carbide Corporation) were addedand mixed at 100 rev/min for 1 hour to obtain Distiller's grain-basedformaldehyde-free glue 7A and 8A.

Test of Distiller's Grain-Based Formaldehyde-Free Adhesive Properties

(a) Preparation of Plywood Samples for Testing

Seven layers of plywood was produced using distiller's grain basednon-formaldehyde glue 1A˜8A from Example 2B.

{circle around (1)} Raw Materials

Veneer sheet size: horizontal sheet size 1230×930 mm, vertical sheetsize 930×615 mm: 100 kg of Distiller's grain-based formaldehyde freeglue 1A˜8A;

{circle around (2)} The specific preparation method for plywood is asfollows:

The horizontal veneers and vertical veneers were passed through a fourroller coating machine to get double side coated with glue. The gluecoated veneers were cross-staggered and cold pressed for 45 minutes.After repairing any defects of the cold-pressed plywood, the staged5-layer plywood was transferred to a hot pressing machine to press for10 minutes at the temperature of 120° C. and a pressure of 100 kg. Aftersanding, the 5-layer plywood was produced. Further coating glue on topand bottom side of the 5-layer plywood and cover two sheets of woodveneers on top and bottom of the 5-layer plywood for cold press. Afterrepairing any defects, the plywood was subjected to hot press under thesame conditions as described above to obtain 7-layers plywood. Theresulting 7-layer plywood was sawn into 8.0 cm×2.5 cm strips asspecimens for testing.

(b) Determination of Dry Shear Strength of the Specimen

The specimens produced using the said distiller's grain basednon-formaldehyde glue 2A, 4A˜8A were stored at room temperature for aweek. Then, the dry shear strength was tested according to GB/T9846-2004method. The 7-layer plywood produced using conventionalurea-formaldehyde and phenol-formaldehyde glue was compared. Testresults are shown in Table 2B.

(c) Determining the Shear Strength of Wet Specimens

7-layer plywood specimen prepared using Distiller's grain basednon-formaldehyde glue 2A, 4A˜8A were immersed in boiling water for 4 h,then separately placed the flat specimen in an air convection dryingoven set at 63±3° C. for 20 h, then immersed the specimen in boilingwater for 4 h again. Removing the specimen from the water and cooling atroom temperature for 10 min. In accordance with GB/T9846-2004 method,the wet shear strength of the specimen was tested. In comparison,7-layer plywood specimen produced using conventional urea-formaldehydeglue and phenol-formaldehyde glue was tested. Test results are shown inTable 2B.

TABLE 2B Dry shear Type of Glue Samples strength, MPas Wet shearstrength, MPas 2A 2.6 0.8 4A 2.0 1.5 5A 3.8 1.8 6A 4.5 1.6 7A 3.2 2.0 8A4.0 2.8 Urea formaldehyde, solid 2.0 dismembered content 50 wt %Phenol-formaldehyde, 4.5 3.5 solid content 50 wt % Note: The higher dryshear strength, the stronger adhesive bonding; the higher the wet shearstrength indicates the better water resistance.

The test results in Table 2B show:

{circle around (1)} The dry shear strength of the plywood produced usingdistiller's grain base formaldehyde-free glue of the present inventionis greater than the plywood produced using urea-formaldehyde glue anddose or equivalent to the plywood produced using phenol-formaldehydeglue, indicating distiller's grain based formaldehyde-free glue has theequivalent degree of adhesive strength to the existing formaldehydeglue. The wet shear strength was significantly higher thanurea-formaldehyde glue, and close to the phenol formaldehyde glue,showing distiller's grain based formaldehyde-free glue has good waterresistance compared to existing formaldehyde glue.

{circle around (2)} 2A and 7A were produced using the same distiller'sgrain based reinforced material sample 2; 6A and 8A were produced usingthe same distiller's grain based reinforced material sample 6. In thepreparation of 7A and 8A, the polyamide epichlorohydrin wet strengthenresin were added, which resulting higher wet shear strength and dryshear strength. This indicates that polyamide epichlorohydrin wetstrengthen agent can improve the bonding strength of sample 7A and 8A,particularly the water resistance has been significantly improved.

(D) Test the Water Resistance of Specimen

1A-8A distiller's grain based formaldehyde-free glue produced 7-layerplywood specimen were placed in water at room temperature for 1 month;at 70° C. and 100° C. water for two hours and 4 hours and then checkedwith the naked eye to observe whether the sheet layers have opened up.In comparison, 7-layer plywood specimen produced using conventionalurea-formaldehyde glue and phenol-formaldehyde glue was tested. Testresults are shown in Table 3B.

TABLE 3B Water at Room 70 C. water 100 C. water Type of glue usedtemperature 1 month 2 hours 4 hours 1A intact intact Partiallydismembered 2A intact intact Intact 3A intact Partially Partiallydismembered dismembered 4A intact intact Intact 5A intact intact Intact6A intact intact Intact 7A intact intact Intact 8A intact intact IntactUrea- dismembered dismembered Dismembered Formaldehyde Phenol- intactintact Intact formaldehyde

Test results as shown in Table 3B indicate that distiller's grain basednon-formaldehyde glue in present invention has better water resistancethan urea-formaldehyde glue, and has equivalent result to phenolformaldehyde glue but achieving no formaldehyde release from the glue.

The Distiller's grain-based formaldehyde-free glue can be used toprepare medium density fiberboard by the conventional method. The testresult of its internal bond strength is 0.70 N/mm2, surface bondingstrength is 0.8 N/mm2, the elastic modulus is 4000 N/mm2, the thicknessswelling (24 h) is less than 15%. It can meet the requirements ofnational standard for medium density fibreboard manufacturing.

The Distiller's grain-based formaldehyde-free glue can be used toprepare chipboard by the conventional method. The test result of itsinternal bond strength is 0.80 N/mm2, the elastic modulus is 3500 N/mm2and the thickness swelling (24 h) is less than 15%. It can meet therequirements of national standard for chipboard. The present inventionutilizes corn and wheat based distiller's grains from byproducts ofbioethanol production to make distiller's grain based reinforcedmaterial and then further formulate the material into distiller's grainbased non-formaldehyde glue. In line with current environmentalrequirements, the invention can achieve the objective of no release offormaldehyde from the glue. It also solves the problems of high cost,easy to spoilage and poor water resistance of biological glue. The gluehas reached and exceeded the adhesion properties and water resistance ofcurrent urea-formaldehyde and phenol formaldehyde. It can be used toprepare various types of wood-based panels.

DESCRIPTION 3 Field of Invention

This invention concerns novel and versatile adhesive products and gluederived from algal materials. In particular, the processed algaladhesive materials have dry and wet strength similar to those producedusing formaldehyde and phenol based processes that are the standardadhesives in industry. Algal based adhesives have the potential toreplace currently used formaldehyde based wood adhesives, thus providinga ‘low carbon, low toxicity and sustainable source of adhesives.Depending on the purity and source of the algal material, the modifiedbio-adhesives can also be used in more demanding ‘niche’ applicationssuch as biomedical, marine, and automotive industrial applications. Theinvention further relates to algal-derived glues and adhesive productscontaining a crosslinked network which can be further processed intopowder form to become adhesive gel or aqueous glue which would beamenable to many industrial manufacturing processes.

Background Art and Related Disclosure

The manufacture of adhesives is a global multi-$Billion industry. Thelargest quantity of adhesive is used in the construction industry forthe production of millions of tonnes of plywood, fibreboard andparticleboard every year.

The huge volume of adhesives manufacture leads to two main problems:

The limited stocks and the price of oil on which much adhesive chemistryis based (formaldehyde and phenol)

The toxicity of the adhesive products due to their containingformaldehyde and phenol Due to the inherently finite nature of fossilfuel resources, the world faces the challenge of finding suitablerenewable substitutes that can begin to replace petrochemicals both as asource of energy and as a source of materials for plastics, rubbers,fertilizers, and fine chemicals.

The other significant issue and cause of public concern is the potentialtoxicity of current adhesives. Organic polymers of either natural orsynthetic origin are the major chemical ingredients in all formulationsof wood adhesives. Urea-formaldehyde is the most commonly used adhesive,which can release low concentrations of formaldehyde from bonded woodproducts under certain service conditions. Formaldehyde is a toxic gasthat can react with proteins of the body to cause irritation and, insome cases, inflammation of membranes of eyes, nose, and throat. It is asuspected carcinogen, based on laboratory experiments with rats and manypeople have identified it as a potential factor in ‘sick building’syndrome.

Phenol-formaldehyde adhesives, which are used to manufacture plywood,flakeboard, and fiberglass insulation, also contain formaldehyde.However, formaldehyde is efficiently consumed in the curing reaction,and the highly durable phenol-formaldehyde, resorcinol-formaldehyde, andphenol-resorcinol-formaldehyde polymers do not chemically break down inservice to release toxic gas. However, it uses the petroleum-basedresource and also expensive.

Increasing environmental concerns and strict regulations on emissions oftoxic chemicals have forced the wood composites industry to developenvironmentally friendly alternative adhesives from abundant renewablesubstances such as soybean protein, animal, casein, vegetable, andblood. Also, adhesives from lignin, tannin, and carbohydrates have beenstudied for replacement of synthetic adhesives that are the mainadhesives used in the manufacture of wood composite products.

However, these types of adhesives suffer from technical disadvantages.These adhesives are generally used for non-structural applications, dueto their poor water resistance and low strength properties.Modifications including further purification to obtain high proteincontents, increases of the specific surface area of the materials,denaturation of the protein by acid, alkaline and surfactants have beenshown to be useful to enhance the wood adhesive strength. However, thesemodifications significantly increase the cost for manufacturing.

It would, therefore, be advantageous to provide adhesives which are ‘lowcarbon and sustainable produced and which have low toxicity but retainthe strength of the current range of formaldehyde or phenol basedadhesives.

One of the possible alternatives to petroleum-based fuels and productsis biomass such as algae. Algae biomass contains lipids, proteins, andcarbohydrates that can be processed into fuels or other valuableco-products through chemical, biochemical, or thermochemical means. Thelipids are of particular interest in current research due to the abilityto use the algal oils to produce biodiesel. Algae stands out from othersources of biomass with respect to lipid production with some estimatesstating that algae is capable of producing up to 30 times as much oilper unit area of land as conventional oilseed crops under idealconditions. Additionally, algae has the added benefit of not competingwith traditional food crops because it can be grown on marginal landsand can utilize brackish or waste water resources.

Other than investigating algal lipids and biodiesel production, thisinvention has focused on the algal mass for use in bio-adhesives in woodcomposite process and other applications. The use of algae as a‘feedstock’ source for the production of adhesives offers the advantagesof ‘low carbon’ processes, sustainability and ‘greener’ productionprocesses.

It is, therefore, a primary objective of the present invention is toprovide a description of an algae-based adhesive which is strong,versatile and inexpensive to manufacture.

It is, therefore, a further object of the present invention to provide astable aqueous adhesive comprising algal-material derived from naturallyoccurring blue algae, brown algae (Phaeophytes), red algae(Rhodophytes), that are safe and water-resistant for wood application.

It is a further object of the present invention to prepare algae basedadhesive products that are produced by mixing dry algae materials withadditives and further milled into fine powder. This acts to increase theadhesive strength and broaden their suitability for adhesiveapplications. This also has the additional advantage of generating aproduct that is easy to store for longer shelf-life and transportation.

It is yet a further objective of the invention to prepare algae basedadhesive products that are produced by mixing dewatered algae materials,e.g. algae blue (water content less than 70%) with additives andhomogenized into aqueous bio-adhesives.

It is yet a further object of the invention to prepare an adhesive thatconsists essentially of byproducts of naturally occurring algal afterbiofuel process.

It is yet a further object of the invention to prepare an adhesive madefrom algae genetically engineered or modified to enhance their growthrate or production efficiency.

It is yet another object of the invention to prepare adhesive productsthat comprise naturally algal materials in dry powder form (less than500 μm) that are blended with a multifunctional crosslinking agent toform a crosslinked network to enhance the water resistance of theadhesives.

It is further another object of the invention to mill the powder to beless than 250 μm for formulation into aqueous adhesives.

It is yet another objective of the invention to prepare adhesiveproducts that comprise above aqueous adhesives and optionally awet-strengthen agent or/and a crosslinking agent for water-resistantwood industry application and other niche applications.

DETAILED DESCRIPTION OF THE INVENTION

The current invention concerns novel bio-adhesives derived from algalmaterials.

According to a first aspect of the invention there is provided algaebased bio-adhesives consisting of algae mass, crosslinking agents andinorganic fillers and optionally other additives for making aqueousalgal bio-adhesives.

According to a second aspect of the invention there is provided aprocess for manufacturing such algal based bio-adhesives, the processcomprising the steps of:

-   -   a. Combining algal material obtained directly from green-blue        algae, red algae, brown algae or biodiesel byproducts of algae        with defined dryness and suitable protein content, a        cross-linking agent, and fillers to form a blend using a        mechanical mixer or blender,

Whereas in step a: the algal material has the water content less than70%; preferably less than 40%; most preferably less than 20%;

the crosslinking agent is selected from a organic polymeric materialwith crosslinkable groups such as poly-isocyanate, epoxy resin, or aninorganic material such as silicates, borates or mixture of polymericcrosslinker and the inorganic substance;

the fillers are calcium materials such as calcium oxide, calciumhydroxide, calcium chloride, calcium carbonate, calcium sulfate,preferably calcium oxide, calcium sulfate which can dewater during theblending process. The algal material in the blend has the contentbetween 50-89%, crosslinking agent has 1.0-20%, and fillers are 10-30%.

-   -   b. Milling the blend via a micronisation milling machine or any        other chosen mechanical milling machine to produce powdery        material with particle size between 30-500 μm, preferably,        between 30-250 μm, most preferably 30-125 μm.    -   c. Mixing the powdery material with water, optionally with        addition of a defoamer or an anti-foaming agent, a thickener and        optionally with a crosslinking agent or wet-strength agent,        wherein defoamer is selected from food grade deformer used in        milk, protein process industry, such as mineral oil, vegetable        oil or white oil based deforming agent; the thickener selected        are food grade water soluble natural polymer such as cellulose        derivatives e.g. HPMC, CMC, proteins such as gelatin, alginate,        chitosan; the wet strength agent is        polyamideamine-epichlorohydrin (PAE), the crosslinking agent is        a polymeric isocyanate with the isocyanate group blocked to        obtain algal aqueous bio-adhesives with solid content between        20-60%, preferably 20-50%, most preferably 20-40%.

According to the invention there is provided a process for manufacturingalgae based bio-adhesives, the process comprising the steps of:

-   -   a. combining algal material, a cross-linking agent and inorganic        fillers to form a blend by mechanical blender;    -   b. Micronising the blend to obtain powdery material; and    -   c. Mixing the powdery material with water, optionally with the        addition of other additives such as defoaming agent, thickener,        wet strength agent and another crosslinking agent to form algal        based bio-adhesives.

In the present invention to make algal based bio-adhesives, the algalmaterials can be obtained from Cladophora, which appears to be one ofthe most abundant types of algae in streams, rivers, and ponds aroundthe world. They can be cultivated in open ponds and closedphotobioreactors. While open pond cultivation requires less energy andhas lower capital cost, photobioreactors have the potential to producelarger quantities of algal biomass and minimize contamination. Inaddition algae can be obtained from unwanted natural incidents ofexcessive local growth. For example, in China, there are bursts of largegrowth of blue algae every year in the national river system and thereare growths (‘blooms’) of red and brown algae along the seashore due toexcessive fertilizer use. The algae materials used from a variety ofsources have been harvested directly by float collection from water orsea or by other common harvesting methods including sedimentation,flocculation, centrifugation, filtration, and flotation with floatcollection. Following harvesting, the algal biomass is typically driedto increase shelf life. Many methods of drying can be used, includingspray-drying, drum-drying, and sun-drying. Typical water content of thealgae after harvesting is around 40-70%. Further drying can obtain a drymass with water content less than 40% and typically less than 20% makingit suitable for the current invention.

Once the algae are dry, the cells must be disrupted to release thelipids for biodiesel production. Cell disruption methods vary accordingto the properties of the algal species used. Some common methods of celldisruption are cell homogenizing, bead milling, ultrasounds,autoclaving, freezing, organic solvents, and enzyme reactions. Thebyproducts after removal of lipids can also be used for currentinvention.

The important byproducts after removal of lipids are proteins andcarbohydrates. Some algae contain up to 60% protein. A well-known algathat is currently cultivated for its protein content is thecyanobacterium species Athrospira, better known as Spirulina.

Spirulina is reported to contain not only around 60% raw protein, butalso vitamins, minerals and many biologically active substances. Itscell wall consists of polysaccharides, has a digestibility of 86percent, and can be easily absorbed by the human body. Spirulina can beeasily cultivated in mass production in china, India and USA. It is oneof the sources of raw algae materials used in the examples in thecurrent invention.

Other algae species are known to have high protein content can also beused as feed materials for the invention as shown in Table 1C. Despiteits high protein content, algae has not gained significant importance asfood or food substitute yet. Strict approval regulations for newfoodstuffs are a barrier, but also the lack of texture and consistencyof the dried biomass, its dark green colour and its slight fishy smellare undesirable characteristics for the food industry. However, thisdoes not affect the uses for this invention.

TABLE 1C General composition of % dry mass of different algae materials(Becker, E. W. (2007). “Micro-algae as a source of protein.”Biotechnology Advances 25(2): 207-210) Alga Protein Carbohydrates LipidsAnabaena cylindrical 43-56 25-30 4-7 Aphanizomenon flos-aquae 62 23 3Chlamydomonas rheinhardii 48 17 21  Chlorella pyrenoidosa 57 26 2Chlorella vulgaris 51-58 12-17 14-22 Dunaliella salina 57 32 6 Euglenagracilis 39-61 14-18 14-20 Porphyridium cruentum 28-39 40-57  9-14Scenedesmus obliquus 50-56 10-17 12-14 Spirogyra sp.  6-20 33-64 11-21Arthrospira maxima 60-71 13-16 6-7 Spirulina platensis 46-63  8-14 4-9Synechococcus sp. 63 15 11 

The crosslinking agent used in current invention is polymeric isocyanatewhich is used to produce polyurethane. The polyisocynate functionalgroups used in current invention include PMDI, PHDI, Polyurethanepre-polymer, blocked polyisocynates such as polyisocyanates with phenol,ε-caprolactam blocked. A blocked polyisocyanate can be defined as anisocyanate reaction product which is stable at room temperature butdissociates to regenerate isocyanate functionality under the influenceof heat around 100-250° C. Blocked polyisocyanates based on aromaticpolyisocyanates dissociate at lower temperatures than those based onaliphatic ones. The dissociation temperatures of blocked polyisocyanatesbased on commercially utilized blocking agents decrease in this order:alcohols>ε-caprolactam>phenols>methyl ethyl ketoxime>active methylenecompounds.

Other crosslinking agent can be used in current invention includeepoxy-resins. Epoxy resins, also known as polyepoxides are a class ofreactive prepolymers and polymers which contain epoxide groups. Epoxyresins are polymeric or semi-polymeric materials and An importantcriterion for epoxy resins is the epoxide content. This is commonlyexpressed as the epoxide number, which is the number of epoxideequivalents in 1 kg of resin (Eq./kg), or as the equivalent weight,which is the weight in grams of resin containing 1 mole equivalent ofepoxide (g/mol). One measure may be simply converted to another:

Equivalent weight(g/mol)=1000/epoxide number(Eq./kg)

The epoxy resin can be used in current invention include Bisphenol Aepoxy resin, Bisphenol F epoxy resin, Aliphatic epoxy resin andGlycidylamine epoxy resin.

The content of the polymeric crosslinking agent mixed with algalmaterials is between 1.0-20%.

Other crosslinking agents can be used include inorganic materials suchas silicates and borates which can be used separately or mixed withabove polymeric crosslinking agent. The total content is in the range of1.0-20%, preferably in the range of 1-10%, most preferably in the rangeof 5-10%.

The fillers used for current application are calcium based inorganicmaterials. They can be used to dewater the algal materials and adjustthe reheological properties of the final bio-adhesives. They can also beuseful to help the subsequent milling process. The more calciummaterials are incorporated, the more dry blend can be obtained. Thetypical content of the calcium materials such as single calcium oxide,calcium chloride calcium carbonate and calcium sulfate or their mixturesis in the range of 10-30%. The optimised composition for easy to millcan be adjusted by changing the ratio of algal mass and the fillers.

After the blending with an industrial mechanical blender, the mixtureneeds to be stored for overnight (>8 hrs) before milling. The purposesof the subsequent milling process has two aspects: one is to break thecell walls of the algal materials to release the protein and the secondis to have a homogenized mixture in powder form to be able to formbio-adhesives for easy to spray or spread for applications. The millingprocess can be performed by readily available micronisation equipments,or mechanical milling machines, including Jet Milling machine, ballmilling machine, mechanical grinding machine etc. The particle sizeobtained is controlled at 30-500 μm, preferably at 30-250 μm, mostpreferably at 30-125 μm.

The algal bio-adhesives can be formulated by adding above milled powderinto premeasured water in a batch vessel with a mixer or pumping into amechanical static mixer with calculated amount of water, or into a batchhomogeniser or online homogeniser including French Press, Manton-Gaulinhomogeniser for continuous formulation of the aqueous bio-adhesives.

The solid content of the formed bio-adhesives is between 20-50% andpreferably between 20-40%.

Optionally, in the formulation of the aqueous bio-adhesives, someadditives can be added during manufacturing to obtain optimizedviscosity and enhanced wet strength for applications.

The additives include defoamer or an anti-foaming agent, a thickener andoptionally with a crosslinking agent or wet-strength agent, whereindefoamer is selected from food grade deformer used in milk, proteinprocess industry, such as mineral oil, vegetable oil or white oil baseddeforming agent; the thickener selected are food grade water solublenatural polymer such as cellulose derivatives e.g. HPMC, CMC, proteinssuch as gelatin, alginate, chitosan etc; the wet strength agent ispolyamideamine-epichlorohydrin (PAE), the crosslinking agent is apolymeric isocyanate with the isocyanate group blocked. The percentageof each additive considered to be added is in the range of 0.01-5%,preferably in the range of 0.1-5%, most preferably in the range of0.5-5%.

The main application of current invention of algal bio-adhesives is inthe field of production of wood based panels to replace formaldehydebased wood adhesives. The wood based panels include plywood, fibreboardand particle board.

The algal bio-adhesives can also be used for making paper-based boardsuch as paper packaging board, cardboard, carton packaging material forrecyclable food packaging, gift packaging and medical packaging. Otherapplications include adhesives for furniture used in hospital andschool. The bio-adhesives can also be used to make fibreboard based onnon-wood materials such as straw. The straw based fibreboard can be usedas packaging materials for food. The algal bio-adhesives can also beused in marine board whereas the highly water-resistant wood board isrequired. Although the invention has been described in connection withspecific preferred embodiments, it should be understood that theinvention as claimed should not be unduly limited to such specificembodiments, various applications of the described modes of carrying outthe invention which are obvious to those skilled in the art are intendedto be covered by the present invention.

The invention now will be further exemplified.

Example 1C Preparation of Algal Bio-Adhesive

Cyanobacteria or blue-green algae was obtained from Tai Lake blue-greenalgae treatment station in China. It was centrifuged to obtain a drymass with 40% water content and the particle size is less than 500 μm.In a mechanical blender (250 KG volume capacity), 70 kg of theblue-green algae, 10 kg of calcium oxide powder (200 meshes) and 10 kgof sodium silicate was added and mixed for 30 mins. To the mixture, 2 kgof PMDI was slowly added during mixing within 20 mins and blended forfurther 30 mins to obtain a well mixed blend. The blend was sealed andstored overnight for 10 hours, and then transferred to an Air-Jetmilling machine to obtain fine powder with particle size around 38 μm.In a 500 L high-shear mixing vessel for producing coating material, 100L water was added, and then 50 kg of above milled powder was added andmixed for 60 mins. 100 g of defoaming agent was added to obtain thealgal bio-adhesives ready for plywood process. The solid content isabout 33%.

Application of Algal Bio-Adhesives for Plywood:

5 pieces of poplar veneers were cut into size at 36 cm×36 cm. The abovealgal bio-adhesive was brushed onto one side of the first piece and oneside of the last piece. Two sides of the rest of 3 pieces. Amount ofbio-adhesives on each veneer was controlled with a balance. 5 pieces ofpoplar veneers were cross-staged. Assembled wood specimens were pressedat 3 MPa and 120° C. for 10 min with a hot press. The wood assemblieswere conditioned at 23° C. and 50% RH for 48 h and then cut into fivepieces with overall dimensions of 80×20 mm and glued dimensions of 20×20mm.

The cut wood specimens were conditioned for 4 additional days at thesame conditions before testing. Shear strength testing was performedusing an Instron (Model 4465; Canton, Mass., USA) at a crosshead speedof 1.6 mm/min according to ASTM Standard Method D906-98(2011). Shearstrength, including dry strength and wet strength, were performedfollowing ASTM Standard Methods (ASTM D906-98 2011) at maximum load wasrecorded. Values reported are the average of five specimen measurements.

Water resistance test: Specimen was boiled at 100° C. for 2 hours. Thespecimen is removed from water and visually inspected for evidence ofdismemberment.

Comparison of Urea-Formaldehyde (UF) glue and Phenol-Formaldehyde (PF)glue to make plywood: Commercially UF and PF for pressing plywood werecarried out as the method shown in Example 1C.

Example 2C: Preparation of Algal Bio-Adhesive

Cyanobacteria or blue-green algae was obtained from Tai Lake blue-greenalgae treatment station in China. It was centrifuged to obtain a drymass with 40% water content. In a mechanical blender (250 KG volumecapacity), 70 kg of the blue-green algae, 10 kg of calcium oxide powder(200 meshes) and 10 kg of sodium silicate was added and mixed for 30mins. To the mixture, 2 kg of PMDI was slowly added during mixing within20 mins and blended for further 30 mins to obtain a well mixed blend.The blend was sealed and stored overnight for 10 hours, and thentransferred to an Air-Jet milling machine to obtain fine powder withparticle size around 38 μm. In a 500 L high-shear mixing vessel forproducing coating material, 150 L water was added, and then 50 kg ofabove milled powder was added and mixed for 30 mins. To the mixture,12.5 kg of PAE and 2.5 kg of PMDI was added and mixed for 60 mins. 100 gof defoaming agent was added to obtain the algal bio-adhesives ready forplywood process. The solid content is about 30%.

The plywood using above algal bio-adhesive was produced according to thesame method as example 1C.

Example 3C: Preparation of Algal Bio-Adhesive

Cyanobacteria or blue-green algae was obtained from Tai Lake blue-greenalgae treatment station in China. It was centrifuged to obtain a drymass with 40% water content. In a mechanical blender (250 KG volumecapacity), 70 kg of the blue-green algae, 10 kg of calcium oxide powder(200 meshes) and 20 kg of sodium silicate was added and mixed for 30mins. To the mixture, 1 kg of PMDI was slowly added during mixing within20 mins and blended for further 30 mins to obtain a well mixed blend.The blend was sealed and stored overnight for 10 hours, and thentransferred to an Air-Jet milling machine to obtain fine powder withparticle size around 125 μm. In a 500 L high-shear mixing vessel forproducing coating material, 100 L water was added, and then 50 kg ofabove milled powder was added and mixed for 30 mins. To the mixture,12.5 kg of PAE and 2.5 kg of PMDI was added and mixed for 60 mins. 100 gof defoaming agent was added to obtain the algal bio-adhesives ready forplywood process. The solid content is about 35%.

The plywood using above algal bio-adhesive was produced according to thesame method as example 1C.

Example 4C: Preparation of Algal Bio-adhesives

Cyanobacteria or blue-green algae was obtained from Tai Lake blue-greenalgae treatment station in China. It was centrifuged to obtain a drymass with 40% water content. In a mechanical blender (250 KG volumecapacity), 70 kg of the blue-green algae, 10 kg of calcium oxide powder(200 meshes) and 20 kg of sodium silicate was added and mixed for 30mins. To the mixture, 1 kg of PMDI was slowly added during mixing within20 mins and blended for further 30 mins to obtain a well mixed blend.The blend was sealed and stored overnight for 10 hours, and thentransferred to an Air-Jet milling machine to obtain fine powder withparticle size around 38 μm. In a 500 L high-shear mixing vessel forproducing coating material, 100 L water was added, and then 50 kg ofabove milled powder was added and mixed for 30 mins. To the mixture, 5.0kg of waterborne blocked polyisocyanates (WB905) was added and mixed for60 mins. 100 g of defoaming agent was added to obtain the algalbio-adhesives ready for plywood process. The solid content is about 35%.

The plywood using above algal bio-adhesive was produced according to thesame method as example 1C.

Example 5C: Preparation of Algal Bio-Adhesive

Spirulina dry powder was obtained commercially and it contains about 60%protein. 10 kg of the algae, 1 kg of calcium oxide powder (200 meshes)and 1 kg of sodium silicate was added and mixed for 30 mins. To themixture, 1 kg of PMDI was slowly added during mixing within 20 mins andblended for further 30 mins to obtain a well mixed blend. The blend wassealed and stored overnight for 10 hours, and then transferred to anAir-Jet milling machine to obtain fine powder with particle size around38 μm. In a 100 L high-shear mixing vessel for producing coatingmaterial, 40 L water was added, and then 10 kg of above milled powderwas added and mixed for 30 mins. To the mixture, 1.0 kg of waterborneblocked polyisocyanates (WB905) was added and mixed for 60 mins. 100 gof defoaming agent was added to obtain the algal bio-adhesives ready forplywood process. The solid content is about 20%.

The plywood using above algal bio-adhesive was produced according to thesame method as example 1C.

Example 6C: Application of Algal Bio-Adhesives for Preparation ofParticle Board

Algal bio-adhesive produced in example 2C was used to prepare particleboard. 150 g of algal bio-adhesive was added slowly to 600 g of pinewood particles having a moisture content of approximately 5% and mixedwith a mechanical mixer. A 9-inch×9 inch×9 inch wood forming box wascentered on a 12 inch×12 inch×0.1 inch stainless steel plate, which wascovered with aluminum foil. The wood-adhesive mixture is slowly addedinto the forming box to achieve a uniform density of particles coatedwith bio-adhesive. The mixture was compressed by hand with a plywoodboard and the wood forming box was carefully removed so that theparticle board matte would not be disturbed. Then, the plywood board wasremoved, a piece of aluminum foil was placed on the matte, and anotherstainless steel plate was placed on top of the matte. The particle boardmatte was then pressed to a thickness of ¾ inch using the followingconditions: 120 psi for 10 minutes at a press platen temperature of 170C. The particle board was trimmed to 5 inches×5 inches to check thewater resistant property.

TABLE 2C Test results of plywood produced from algal bio-adhesives inexample 1C-6C Water resistance test Dry strength Wet strength (boilingwater for two Plywood (MPa) (MPa) hours) Example 1C 1.8 0.8 IntactExample 2C 3.0 1.5 Intact Example 3C 2.5 1.0 Intact Example 4C 2.5 1.0Intact Example 5C 3.5 1.6 Intact Example 6C / / Intact Formaldehyde-Urea2.5 / Dismembered resin Phenol-Urea resin 3.4 1.8 intact

1. An algal bio-adhesive comprising algae mass, a crosslinking agent andan inorganic filler.
 2. The algal bio-adhesive according to claim 1,comprising a defoaming agent.
 3. The algal bio-adhesive according toclaim 1, comprising: 20 to 60% by weight solid content, and 40 to 80% byweight liquid content, in which the solid content comprises: 50 to 89%by weight of algae mass; 1 to 20% by weight of a crosslinking agent; and10 to 30% by weight of inorganic filler.
 4. The algal bio-adhesiveaccording to claim 3, in which the liquid content comprises water, andoptionally 0.01 to 5% by weight of a defoaming agent.
 5. The algalbio-adhesives according to claim 1, wherein the algae mass comprises atleast one of blue-green algae, red algae, and brown algae, which can beharvested from river and ocean.
 6. The algal bio-adhesives according toclaim 1, wherein the algae mass comprises algae cultivated in at leastone of a pond or photobioreactor.
 7. The algal bio-adhesives accordingto claim 1, wherein the algae mass comprises genetically modified orenhanced or selected algae cultivated in a pond or photobioreactor. 8.The algal bio-adhesives according to claim 1, wherein the algae mass hasa water content less than 70%, preferably less than 40%, most preferablyless than 20%.
 9. The algal bio-adhesives according to claim 1, whereinthe algae mass is from a biodiesel process by-product of algae.
 10. Thealgal bio-adhesives according to claim 1, wherein the crosslinking agentis selected from the group consisting of: at least one syntheticpolymeric crosslinking agent; at least one inorganic material; and amixture of at least one synthetic polymeric crosslinking agent and atleast one inorganic material.
 11. The algal bio-adhesives according toclaim 10, in which the synthetic polymeric crosslinking agents areselected from the group consisting of: polyisocyanates, polyisocyanateswith blocked isocyanate groups and epoxy resins; and the inorganicmaterials are selected from the group consisting of: silicates andborates.
 12. The algal bio-adhesives according to claim 1, wherein thefiller comprises at least one calcium compound selected from the groupconsisting of: calcium oxide, calcium sulfate, calcium carbonate andcalcium hydroxide.
 13. The algal bio-adhesives according to claim 1,comprising at least one additive selected from the group consisting of:at least one defoaming agent, at least one wet strength agent, at leastone thickener and at least one crosslinking agent.
 14. A method forpreparing algal bio-adhesives according to claim 1, comprising the stepsof: a. combining algal mass, a cross-linking agent, and fillers to forma blend using a mechanical mixer or blender, b. milling the blend via amicronization milling machine or any other chosen mechanical millingmachine to produce powdery material with particle size between 30-500μm, preferably, between 30-250 μm, most preferably 30-125 μm, c. mixingthe powdery material with water, optionally with addition of otheradditives.
 15. The method according to claim 14, wherein the blendconsists 50-89% of the algal mass, 1.0-20% of crosslinking agent and10-30% of fillers.
 16. The method according to claim 14, in which thepercentage of each additive used to form aqueous bio-adhesives isbetween 0.01-5%, preferably 0.1-5%.
 17. The method according to claim14, wherein the additives comprise at least one defoaming agent whichis: a silicone-based defoaming agent; a polyether based defoaming agent;a higher alcohol defoaming agent; or a food grade defoaming agent, suchas mineral oil, vegetable oil or white oil based defoaming agent. 18.The method according to claim 14, wherein the additives comprise atleast one thickener which is a water soluble natural polymer such ascellulose derivatives, proteins, alginate and chitosan.
 19. The methodaccording to claim 14, wherein the additives comprise a wet strengthagent which is polyamideamine-epichlorohydrin (PAE).
 20. The methodaccording to claim 14, wherein the crosslinking agent is a polymericisocyanate with the isocyanate group blocked.
 21. The method accordingto claim 14, in which the algal bio-adhesive has a solid content between20-60%, preferably 20-50%, most preferably 20-40%.
 22. The algalbio-adhesive according to claim 1, for use in at least one applicationselected from the group consisting of: wood panel process as substituteof formaldehyde based wood adhesives; water-resistant glue for paperpackaging industry; and hospital and school building board decoration,assembling and construction.